Oil Sands Process-affected Water Research Articles

Persulfate Oxidation Coupled with Biodegradation by Pseudomonas fluorescens Enhances Naphthenic Acid Remediation and Toxicity Reduction.

The extraction of bitumen from the Albertan oilsands produces large amounts of oil sands process-affected water (OSPW) that requires remediation. Classical naphthenic acids (NAs), a complex mixture of organic compounds containing O2− species, are present in the acid extractable organic fraction of OSPW and are a primary cause of acute toxicity. A potential remediation strategy is combining chemical oxidation and biodegradation. Persulfate as an oxidant is advantageous, as it is powerful, economical, and less harmful towards microorganisms. This is the first study to examine persulfate oxidation coupled to biodegradation for NA remediation. Merichem NAs were reacted with 100, 250, 500, and 1000 mg/L of unactivated persulfate at 21 °C and 500 and 1000 mg/L of activated persulfate at 30 °C, then inoculated with Pseudomonas fluorescens LP6a after 2 months. At 21 °C, the coupled treatment removed 52.8–98.9% of Merichem NAs, while 30 °C saw increased removals of 99.4–99.7%. Coupling persulfate oxidation with biodegradation improved removal of Merichem NAs and chemical oxidation demand by up to 1.8× and 6.7×, respectively, and microbial viability was enhanced up to 4.6×. Acute toxicity towards Vibrio fischeri was negatively impacted by synergistic interactions between the persulfate and Merichem NAs; however, it was ultimately reduced by 74.5–100%. This study supports that persulfate oxidation coupled to biodegradation is an effective and feasible treatment to remove NAs and reduce toxicity.

Detection of naphthenic acid uptake into root and shoot tissues indicates a direct role for plants in the remediation of oil sands process-affected water

Bitumen extraction from surface-mined oil sands deposits results in the accumulation of large volumes of oil sands process-affected water (OSPW). Naphthenic acids (NAs) are primary contributors to OSPW toxicity and have been a focal point for the development of OSPW remediation strategies. Phytoremediation is an approach that utilizes plants and their associated microbes to remediate contaminants from soil and groundwater. While previous evidence has indicated a role for phytoremediation in OSPW treatment through the transformation and degradation of NAs, there are no reports that demonstrate the direct uptake of NAs into plant tissue. Using NAs labelled with 14C radioisotopes (14C-NAs) paired with whole-plant autoradiography, we show that NAs representing aliphatic (linear), single-ring, and diamondoid compounds were effectively removed from hydroponic solution and OSPW-treated soil by sandbar willow (Salix interior) and slender wheatgrass (Elymus trachycaulus) and their associated microbiomes. The NA-derived 14C label accumulated in root and shoot tissues of both plant species and was concentrated in vascular tissue and rapidly growing sink tissues, indicating that 14C-NAs or their metabolic derivatives were incorporated into physiological processes within the plants. Slender wheatgrass seedlings grown under axenic (sterile) hydroponic and soil conditions also effectively removed all 14C-NAs, including a highly stable diamondoid NA, demonstrating that plants can directly take up simple and complex NAs without the assistance of microbes. Furthermore, root and shoot tissue fractionation into major biomolecule groups suggests that NA-derived carbon is allocated toward biomolecule synthesis rapidly after NA treatment. These findings provide evidence of plant-mediated uptake of NAs and support a direct role for plants and their associated microbes in the development of future large-scale OSPW phytoremediation strategies.

Complete Genome Sequence of a Pseudomonas Species Isolated from Tailings Pond Water in Alberta, Canada.

We report the complete genome sequence of strain OST1909, belonging to a Pseudomonas species. The genome size is 6,306,352 bp, with a G+C content of 59.6%. The isolate was recovered from oil sands process-affected water (OSPW), despite the numerous toxic compounds that accumulate in oil sands tailings ponds.

Preparative isolation, fractionation and chemical characterization of dissolved organics from natural and industrially derived bitumen-influenced groundwaters from the Athabasca River watershed

Recent analytical advances have provided evidence that groundwater affected by oil sands process-affected water (OSPW) is reaching the Athabasca River at one location. To understand and discriminate the toxicological risks posed by OSPW-influenced groundwater relative to groundwaters associated with natural oil sands deposits, these highly complex mixtures of soluble organics were subjected to toxicological characterization through effects directed analysis. A recently-developed preparative fractionation methodology was applied to bitumen-influenced groundwaters and successfully isolated dissolved organics from both industrial and natural sources into three chemically distinct fractions (F1, F2, F3), enabling multiple toxicological assessments. Analytical techniques included electrospray ionization high resolution mass spectrometry (ESI-HRMS), liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF/MS), gas chromatography mass spectrometry (GC–MS), and synchronous fluorescence spectroscopy (SFS) methods, which did not reveal obvious differences between sources. Comparisons between fractions within each source consistently demonstrated that F3 contained compounds with greater polarity than F2, which in turn was more polar than F1. The abundance of O2 species was confined to F1, including naphthenic acids often cited for being the primary toxicants within bitumen-influenced waters. This result is consistent with earlier work on aged OSPW, as well as with other extraction methods, suggesting that additional factors other than molecular weight and the presence of acid functionalities play a prominent role in defining compound polarities and toxicities within complex bitumen-derived organic mixtures. The similarities in organic abundances, chemical speciation, aromaticity, and double bond equivalents, concomitant with inorganic mixture similarities, demonstrate the resemblances of bitumen-influenced groundwaters regardless of the source, and reinforce the need for more advanced targeted analyses for source differentiation. • Method for extraction and fractionation of dissolved organics was applied to bitumen-influenced groundwater samples • Dissolved organics are considered principal toxic components in OSPW • Three large volume organic fractions were generated and characterized by complement of methodologies • Isolated fractions increased in polarity and degree of aromaticity • Chemical composition was similar between groundwaters influenced by OSPW and/or natural bitumen sources

Treatment of oil sands process affected waters by constructed wetlands: Evaluation of designs and plant types

Constructed wetland treatment systems (CWTS)s can be used to treat various wastewaters. The main constituent in oil sands process-affected water (OSPW) with uncertain treatment by CWTS are naphthenic acid fraction compounds (NAFC)s. The NAFCs are also among the primary contributors of toxicity to aquatic organisms. While there is preliminary evidence that some CWTSs are capable of treating OSPW for future potential discharge, there is little information comparing the effectiveness and efficiencies of different CWTS designs.Obtaining large volumes of OSPW for testing can be difficult, and while it is known that synthetic NAFCs are simpler and have different toxicity than OSPW-NAFCs, it is unknown whether they could serve as a proxy for optimization of CWTS design and operation. This study presents a comprehensive comparison of CWTS performance operated with both synthetic OSPW and OSPW for four CWTS designs differing in plant type, aeration, flow path, water depth, and substrate type. This study evaluated the potential biodegradation of NAFCs including: (1) decrease in total NAFC concentration, (2) shifts in Ox-NAFC fractions from O2- to O3-, O4-, and O5-NAFC, (3) decrease in carbon number, (4) decrease of the double bond equivalencies (DBE), and (5) change in toxicity of the waters to test organisms.CWTS planted with Sedge achieved the greatest extent of NAFC treatment and detoxification regardless of design. Although CWTSs planted with Cattail and Bulrush also degraded NAFCs and decreased toxicity, a greater hydraulic retention time was required, and the total extent of treatment was less than the CWTSs planted with Sedge. While synthetic OSPW was more toxic and experienced faster degradation rates, it showed similar trends to OSPW in terms of CWTS design efficiencies and function. Although synthetic OSPW would not be appropriate for modelling or scaling of CWTSs, it can be useful for testing designs and operating conditions.

The Appropriateness of Using Aquatic Snails as Bioindicators of Toxicity for Oil Sands Process-Affected Water

Canada’s oil sands mining activity produces large volumes of oil sands process-affected water (OSPW), and there have been increasing concerns regarding the potential environmental impacts associated with this material. Developing an understanding of the toxicity of OSPW is critical to anticipating and mitigating the potential risks and effects of the oil sands industry on surrounding ecosystems. The composition of OSPW is highly variable and is influenced by a range of factors. While numerous research projects have been conducted on the toxicity of OSPW, much remains unknown about its impact on various biota. Freshwater gastropods (snails and slugs) are an ecologically crucial aquatic group, and members of this taxa have been used as bioindicators in a range of ecological settings. The literature suggests freshwater snails could be used as an indicator of toxicity in monitoring programs associated with oil sands development. This mini-review explores the use of snails as bioindicators in aquatic systems affected by oil sands development, focusing on how snails may respond to potential constituents of concern in systems exposed to OSPW.

Effects of Oil Sands Process-Affected Water on Measured Concentrations of Polycyclic Aromatic Hydrocarbons

The assessment of risks and remediation of oil sands process-affected water (OSPW) requires an understanding of possible interactions of naturally occurring surfactants with hydrophobic organic com...

Non-target profiling of bitumen-influenced waters for the identification of tracers unique to oil sands processed-affected water (OSPW) in the Athabasca watershed of Alberta, Canada.

RationaleThe objective of this study was to identify unique chemical tracers of oil sands process‐affected water (OSPW) to enable definitive discrimination of tailings pond seepage from natural bitumen‐influenced waters from the Canadian Alberta McMurray formation.MethodsThe approach involved comparing unknowns from an unprecedented sample set of OSPW (n = 4) and OSPW‐affected groundwaters (n = 15) with natural bitumen‐influenced groundwaters (n = 20), using high‐performance liquid chromatography/electrospray ionisation high‐resolution mass spectrometry (HPLC/ESI‐HRMS) operated in both polarities.ResultsFour unknown chemical entities were identified as potential tracers of OSPW seepage and subsequently subjected to structural elucidation. One potential tracer, tentatively identified as a thiophene‐containing carboxylic acid [C15H23O3S]−, was only detected in OSPW and OSPW‐affected samples, thereby showing the greatest diagnostic potential. The remaining three unknowns, postulated to be two thiochroman isomers [C17H25O3S]+ and an ethyl‐naphthalene isomer [C16H21]+, were detected in one and two background groundwaters, respectively.ConclusionsWe advanced the state of knowledge for tracers of tailings seepage beyond heteroatomic classes, to identifying diagnostic substances, with structures postulated. Synthesis of the four proposed structures is recommended to enable structural confirmations. This research will guide and inform the Oil Sands Monitoring Program in its efforts to assess potential influences of oil sands development on the Athabasca River watershed.

Developments in Molecular Level Characterization of Naphthenic Acid Fraction Compounds Degradation in a Constructed Wetland Treatment System

The reclamation of oil sands process-affected water (OSPW) is a matter of environmental importance because of the aquatic toxicity to biota. This study describes refinements in advanced analytical methods to assess the performance of biological treatment systems for OSPW, such as constructed wetland treatment systems (CWTSs). Assessment of treatment efficiency by measurement of the degradation of naphthenic acid fraction compounds (NAFCs) in OSPW is challenging in CWTS due to potentially interfering constituents such as humic acids, organic acids, salts, and hydrocarbons. Here we have applied a previous weak anion exchange (WAX) solid-phase extraction (SPE) method and high-resolution Orbitrap-mass spectrometry (MS) to remove major interferences from the NAFC analysis. The refinements in data processing employing principal component analysis (PCA) indicates that the relative abundance of NAFCs decreased with time in the treated OSPW relative to the untreated OSPW. The most saturated NAFCs with higher carbon numbers were relatively more degraded as compared to unsaturated NAFCs. The use of Kendrick plots and van Krevelen plots for assessment of the performance of the CWTS is shown to be well-suited to detailed monitoring of the complex composition of NAFCs as a function of degradation. The developments and application of analytical methods such as the WAX SPE method and high-resolution Orbitrap-MS are demonstrated as tools enabling the advancement of CWTS design and optimization, enabling passive or semi-passive water treatment systems to be a viable opportunity for OSPW treatment.

Investigating the mechanism of vanadium toxicity in freshwater organisms

Vanadium (V) could present a risk for aquatic organisms from the Alberta oil sands region, if present in high concentrations. An industry pilot project has used petroleum coke (PC) as a sorbent to remove organic toxicants from oil sands process-affected water (OSPW), but it also caused V to leach from PC into the OSPW, reaching concentrations of up to 7 mg V/L (a level known to be toxic to aquatic organisms). Vanadium is a transition metal with several oxidation states, which could potentially elicit its toxicity through either ion imbalance or oxidative stress. This study investigated the effect of V on Daphnia magna and Oncorhynchus mykiss. Daphinds and O. mykiss were exposed to concentrations of V up to their respective calculated median lethal concentration (LC50): 3 mg V/L for D. magna and 7 mg V/L for O. mykiss. For both organisms, the influence of V on sodium flux and whole body sodium was evaluated. Its effect on whole body calcium and the oxidative stress responses in O. mykiss at the gill and liver levels was also studied. Results suggested that 3.1 mg V/L for D. magna and 6.8 mg V/L for O. mykiss caused an overall increase in sodium influx in both the daphnids and rainbow trout. However, concentrations of V ranging between 0.2 and 4 mg V/L for D. magna and 1.8 and 6 mg V/L for O. mykiss reduced whole body sodium in both organisms and whole body calcium in O. mykiss. Concentrations above 3.6 mg V/L caused significant lipid peroxidation in the gills and liver of rainbow trout, while 1.9 mg V/L produced a substantial decrease in the fish gill GSH:GSSG ratio, but no change in the ratio between these thiols in the liver. Concentrations of 6.62 mg V/L sharply increased catalase activity in the liver but not in the gills. Neither liver nor gill superoxide dismutase was altered by V. Overall, results suggest that both ion imbalance and oxidative stress are part of the mechanism of toxicity of V in D. magna and O. mykiss and that further research is warranted to fully elucidate the mechanism(s) of V toxicity in aquatic organisms.

Treatment of Polycyclic Aromatic Hydrocarbons in Oil Sands Process-Affected Water with a Surface Flow Treatment Wetland

This study applied a passive sampling approach using low-density polyethylene passive samplers to determine the treatment efficiency of the Kearl surface flow treatment wetland for polycyclic aromatic hydrocarbons (PAHs) in Oil Sands Process-affected Waters (OSPW). Treatment efficiency was measured as concentration-reduction and mass-removal from the OSPW. The results show that the wetland’s ability to remove individual PAHs from the influent varied substantially among the PAHs investigated. Treatment efficiencies of individual PAHs ranged between essentially 0% for certain methylated PAHs (e.g., 2,6-dimethylnaphthalene) to 95% for fluoranthene. Treatment in the Kearl wetland reduced the combined total mass of all detected PAHs by 54 to 83%. This corresponded to a reduction in the concentration of total PAHs in OSPW of 56 to 82% with inflow concentrations of total PAHs ranging from 7.5 to 19.4 ng/L. The concentration of pyrene in water fell below water quality targets in the Muskeg River Interim Management Framework as a result of wetland treatment. The application of the passive samplers for toxicity assessment showed that in this study PAHs in both the influent and effluent were not expected to cause acute toxicity. Passive sampling appeared to be a useful and cost-effective method for monitoring contaminants and for determining the treatment efficiency of contaminants in the treatment wetland.

Isomer-specific monitoring of naphthenic acids at an oil sands pit lake by comprehensive two-dimensional gas chromatography–mass spectrometry

Naphthenic acids (NAs) are persistent, toxic contaminants that are found to accumulate in oil sands process-affected water (OSPW) and tailings after bitumen extraction. A number of strategies for the reclamation of oil sands tailings are currently being tested, including the development of the first demonstration pit lake by Syncrude Canada, Base Mine Lake (BML). An important component of reclamation activities is understanding the source and cycling of NAs in such reclamation systems. However, NAs exist as a highly complex mixture of thousands of compounds which makes their analysis an ongoing challenge. Herein, comprehensive two-dimensional gas chromatography coupled to time of flight mass spectrometry (GC × GC/TOFMS) was used to analyze the methylated extracts of water samples from the water cap and fluid fine tailings (FFT) deposit of BML to characterize the variations in NA distributions between geochemical zones. A collection of (alkylated) monocyclic-, bicyclic-, adamantane-, and thiophene-type carboxylic acids were identified. Total relative abundances were calculated for each NA class (by summation of peak areas of all detected isomers) and minimal variability was detected in the water cap. Total relative abundances for each NA class were either similar or higher in the FFT, relative to the water cap. Examination of isomer distributions indicated that differences in abundance values were generally driven by variations in only one or two isomers of a given NA class. Furthermore, GC × GC revealed distinct isomer profiles were observed between two FFT samples and between the FFT and water cap. While it is not yet clear whether these differences are due to differences in sources of NAs or in their environmental processing, these results illustrate the capability of GC × GC to investigate these questions and thus contribute to the management of these compounds within reclamation or environmental systems.

Mechanisms of pH-Dependent Uptake of Ionizable Organic Chemicals by Fish from Oil Sands Process-Affected Water (OSPW).

Uptake and effects of ionizable organic chemicals (IOCs) that are weak acids in aqueous solution by fish can differ as a function of pH. While the pH-dependent behavior of select IOCs is well-understood, complex mixtures of IOCs, e.g., from oil sands process-affected water (OSPW), have not yet been studied systematically. Here, we established an in vitro screening method using the rainbow trout gill cell line, RTgill-W1, to investigate pH-dependent cytotoxicity and permeation of IOCs across cultured epithelia using ultra-high-performance liquid chromatography with high-resolution mass spectrometry (UPLC-HRMS). The assay was benchmarked using model chemicals and technical mixtures, and then used to characterize fractions and reconstituted extracts of field-collected OSPW. Significant pH-dependent cytotoxicity of individual IOCs, acidic fractions, and reconstituted extracts of OSPW was observed. In vitro data were in good agreement with data from a 96 h in vivo exposure experiment with juvenile rainbow trout. Permeation of some IOCs from OSPW was mediated by active transport, as revealed by studies in which inhibitors of these active transport mechanisms were applied. We conclude that the RTgill-W1 in vitro assay is useful for the screening of pH-dependent uptake of IOCs in fish, and has applications for in vitro-in vivo extrapolation, and prioritization of chemicals in nontarget screenings.

Microbial electrochemical biosensor for rapid detection of naphthenic acid in aqueous solution

Abstract In processed water generated from oil sands operations, naphthenic acids (NAs) are identified as one of the primary sources of acute toxicity and were assessed for their endocrine-disrupting potentials. Hence, the monitoring of NAs in aqueous environmental matrices is crucial for oil sands and crude oil production industries. Commonly used analytical methods for NAs include Fourier transform infrared spectroscopy, gas chromatography–mass spectrometry, and high-performance liquid chromatography. However, these methods are time-consuming, expensive, and samples must be sent to an analytical lab for analysis. In this study, we first demonstrated microbial electrochemical cell (MXC)-based biosensor for the rapid detection of a model NA compound (cyclohexane carboxylic acid) in water samples. Under the continuous closed-circuit operation of MXC biosensor, electrical responses (peak currents) were fairly proportional (R2 = 0.64) to the model NA concentrations ranging from 50 to 250 mg COD/L. However, the charging-discharging operation of biosensor significantly increased the peak currents by 90–124 folds higher than that observed for continuous closed-circuit operation. Besides, a linear relationship between model NA concentrations and the peak currents (R2 = 0.96) was observed. Furthermore, it has been revealed that the biosensor would be sensitive to salinity levels and temperature changes; however, once calibrated it can be used for measurement of model NA concentrations. Overall, the results of this study demonstrated that with further development, MXC biosensor could be used as a simple bioanalytical tool for monitoring NA concentrations in oil sands process-affected water.

Oil sands process affected water sourced Trichoderma harzianum demonstrates capacity for mycoremediation of naphthenic acid fraction compounds

Development of Alberta’s oil sands requires large volumes of water, leading to the abundance of oil sands process affected water (OSPW) that must be remediated prior to discharge or reuse. OSPW contains a variety of dissolved organic compounds, however naphthenic acids (NAs) have been found to contribute significantly to the toxicity of OSPW. A fungus, Trichoderma harzianum, isolated directly from OSPW, has previously demonstrated a high tolerance and capacity for growth in the presence of commercial NAs. This study conducted microcosm experiments to elucidate and characterize the capacity of T. harzianum to degrade labile commercial NAs (Merichem), and OSPW-sourced naphthenic acid fraction compounds (NAFCs). Additionally, two model NA compounds, the simple single ring cyclohexane carboxylic acid (CHCA) and complex diamondoid 1-adamanatane carboxylic acid (ADA), were utilized to determine the influence of NA structure on degradation. T. harzianum degraded 14% of CHCA, 13% of ADA, and 23–47% of Merichem NAs. Additionally, Orbitrap mass spectrometry revealed a large change in Z-series within NAFCs. This removal and shift in composition correlated to a 59% and 52% drop in toxicity as per Microtox, for Merichem NAs and NAFCs respectively. This proof of concept experiment confirms that the fungal species T. harzianum can contribute to the biodegradation of complex dissolved organics found in OSPW, including cyclic and diamondoid structures.

Effects of Hydrocarbons on Wind Waves in a Mine Pit Lake

The extraction and upgrading of bitumen to crude oil from the Canadian oil sands has produced large quantities of byproducts such as fluid fine tailings (FFT) and oil sands process affected water (OSPW). One reclamation strategy for these byproducts is to backfill a mined-out pit with FFT and cap it with a mix of OSPW and non-process affected water to form a pit lake. We investigated the effects of hydrocarbons, residual bitumen, on the generation and growth of wind waves, both in the laboratory and in a pit lake. In the laboratory, we compared the wind wave characteristics in the presence and absence of a hydrocarbon film. We showed that the hydrocarbon film dampens high frequency waves, resulting in a slower growing wave field dominated by lower frequency waves. These results were consistent with our field observations. Thus, it appears that the presence of a hydrocarbon film on a pit lake leads to a wind wave field dominated by longer wavelength waves that take more time to develop and grow at a slower rate. This is important since wind wave-driven mixing, in tandem with biogeochemical processes, governs water quality in mine pit lakes. Thus, this work improves understanding of the physical processes that effect water quality in mine pit lakes and enhances the ability of mine managers to conduct pit lake reclamation.

Inorganic fraction of oil sands process-affected water induces mammalian macrophage stress gene expression and acutely modulates immune cell functional markers at both the gene and protein levels

The focus of the present study was to examine the acute immunotoxic properties of oil sands process-affected waters (OSPW) using the RAW 264.7 macrophage cell line. Specifically, we used a quantitative PCR assay to monitor changes in the expression of stress, cytokine, and antimicrobial enzyme genes in activated macrophages following acute (i.e. < 24 h) exposure of the cells to whole OSPW and its fractions. Overall, our data shows that OSPW inorganic fraction (IF) significantly induces the expression of genes associated with oxidative stress and DNA damage and that the OSPW-IF also significantly augmented cytokine gene expression. These effects are similar to what was observed following whole OSPW exposures, which contrasts the minimal effects observed when cells were treated with equivalent doses of the OSPW organic fraction (OF). Surprisingly, OSPW-IF had reciprocal effects on gene and protein expression levels of two key macrophage enzymes (e.g. inducible nitric oxide (iNOS) synthase and arginase), which indicates that components within OSPW-IF have the unique ability to alter the overall functional states of macrophage by polarizing them towards an alternatively activated status; concomitant with the reciprocal depression of iNOS levels and enhanced expression and activity of arginase. Collectively, these findings show that at sub-lethal exposure doses, the inorganic constituents of OSPW have significant immunotoxicological properties that could potentially affect innate cellular defense responses of exposed animals.

Investigating the toxicity of naphthenic acid fraction components from oil sands process-affected water to developing fathead minnow (Pimephales promelas)

The extraction of bitumen from Alberta’s oil sands region generates large volumes of oil sands process-affected water (OSPW) that is stored in tailings ponds. Toxic constituents present in OSPW such as naphthenic acid fraction components (NAFCs) can cause adverse effects to aquatic life. Recent research has focused on the toxicity of NAFCs to highly vulnerable early life stages of fish. Here we examined the embryotoxicity of NAFCs (0-54 mg/L) extracted from OSPW to native fathead minnow (Pimephales promelas) from 1-day post-fertilization to hatch in a semi-natural setting at Queen’s University’s Biological Station. Embryo heart rate, mortality, prevalence and severity of malformations at hatch, post-hatch mass, and basal activity at hatch was examined. Embryo heart rates declined with increasing NAFC concentration, preceding pronounced exposure-response patterns of mortality and non-viable hatches. Visible malformations included cardiovascular (pericardial edema; present in 81.51% of non-viable hatches), craniofacial (reduced jaw and head size; 68.96%), myoskeletal (spinal curvatures; 60.90%), and peritoneal (yolk sac edema; 26.44%) malformations, that significantly increased in severity with increasing NAFC concentration. Fish that survived lethal concentrations displayed evidence of nervous system impairment including elevated patterns of erratic twitching. Post-hatch mass generally increased with increasing NAFC exposure, potentially as a compensatory-like response. Results of this work are the first to be reported in a semi-natural exposure setting and provide important toxicological information that will aid future policy directives for the management of OSPW in Alberta, Canada.

Effects of chemical fractions from an oil sands end-pit lake on reproduction of fathead minnows

Oil sands process-affected water (OSPW) is a byproduct of bitumen extraction in the surface-mining oil sands industry in Alberta, Canada. Organic compounds in OSPW can be acutely or chronically toxic to aquatic organisms, so part of a long-term strategy for remediation of OSPW is ageing of water in artificial lakes, termed end-pit lakes. BaseMine Lake (BML) is the first oil sands end-pit lake, commissioned in 2012. At the time of its establishment, an effects-directed analysis of BML-OSPW showed that naphthenic acids and polar organic chemical species containing sulfur or nitrogen contributed to its acute lethality. However, the chronic toxicity of these same chemical fractions has not yet been investigated. In this work, the short-term fathead minnow reproductive bioassay was used to assess endocrine-system effects of two fractions of BML-OSPW collected in 2015. One of the fractions (F1) contained predominantly naphthenic acids, while the other (F2) contained non-acidic polar organic chemical species. Exposure of minnows to F1 or F2 at concentrations equivalent to 25% (v/v) of the 2015 BML-OSPW sample (5–15% of the 2012 BML-OSPW sample) did not alter reproductive performance, fertilization success, or concentrations of sex steroids in female or male minnows. Additionally, there were no significant differences in fertility, hatching success, or incidence of morphological indices of embryos collected on day 7 or 14 from exposed breeding trios. However, exposure of male fathead minnow to 25% (v/v) intact 2015 BML-OSPW resulted in a significantly greater hepatosomatic index. Exposure of fathead minnow to refined fractions of dissolved organic chemicals in 2015 BML-OSPW, or a 25% (v/v) of the intact mixture did not affect fertility or fecundity as measured by use of the 21-day reproductive bioassay. These data will be useful in setting future threshold criteria for OSPW reclamation and treatment.

Direct analysis of naphthenic acids in constructed wetland samples by condensed phase membrane introduction mass spectrometry.

The application of direct mass spectrometry techniques to the analysis of complex samples has a number of advantages including reduced sample handling, higher sample throughput, in situ process monitoring, and the potential for adaptation to on-site analysis. We report the application of a semi-permeable capillary hollow fibre membrane probe (immersed directly into an aqueous sample) coupled to a triple quadrupole mass spectrometer by a continuously flowing methanol acceptor phase for the rapid analysis of naphthenic acids with unit mass resolution. The intensity of the naphthenic acid-associated peaks in the mass spectrum are normalized to an internal standard in the acceptor phase for quantitation and the relative abundance of the peaks in the mass spectrum are employed to monitor compositional changes in the naphthenic acid mixture using principle component analysis. We demonstrate the direct analysis of a synthetic oil sands process-affected water for classical naphthenic acids (CnH2n+zO2) as they are attenuated through constructed wetlands containing sedge (Carex aquatilis), cattail (Typha latifolia), or bulrush (Schoenoplectus acutus). Quantitative results for on-line membrane sampling compare favourably to those obtained by solid-phase extraction high-resolution mass spectrometry. Additionally, chemometric analysis of the mass spectra indicates a clear discrimination between naphthenic acid-influenced and natural background waters. Furthermore, the compositional changes within complex naphthenic acid mixtures track closely with the degree of attenuation. Overall, the technique is successful in following changes in both the concentration and composition of naphthenic acids from synthetic oil sands process-affected waters, with the potential for high throughput screening and environmental forensics.